Imaam Ghazaali (r.a) reported that Moosa عليه السلام asked Hazrat Khidr عليه السلام to advise him. He said,

"Be someone who constantly smiles, and not someone who is constantly angry. Be someone who benefits others, and not someone who harms others. Refrain from argumentation. Do not walk around without purpose. Do not laugh without a reason. Do not disparage wrongdoers by mentioning their mistakes to them. And cry over your misdeeds, O son of 'Imraan."